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Food Safety Focus (134th Issue, September 2017) – Food Incident Highlight

Mysterious Metallic Colours on Meat

From time to time, the Centre for Food Safety received complaints about the presence of shiny metallic colours on the cut surface of meat such as poultry meat. Some members of the public may have concerns about food safety regarding these mysterious iridescent colours on meat.

Iridescence is a physical phenomenon that results in shiny, rainbow-like colours (e.g. green, red, orange) seen in raw and cooked meat products, e.g. sliced roast beef and ham products. Meat contains iron, fat, and other compounds. The commonly accepted mechanism for iridescence involves optical light diffraction resulting from muscle’s striated structure and fibrous nature. When light hits a slice of meat, it splits into colours like a rainbow. There are various pigments in meat compounds that can give it an iridescent or greenish cast when exposed to heat and processing. According to overseas food safety authorities, iridescence does not represent decreased quality or safety of the meat.